Breaking down feral hog myths

Highest ranking among the myths are estimates of the actual number of feral hogs in Texas, Higginbotham said. A common number that has been bandied about for years is 1 to 4 million. But there was just no data to support this estimate.
That is, not until Dr. Roel Lopez recently used geographic information system procedures to turn the guesstimates into reliable estimates.

Robert Burns, Texas AgriLife | Mar 30, 2011

Until recently, if anyone tried to tell you how many feral hogs there are in Texas, they were just blowing smoke, according to a Texas AgriLife Extension Service wildlife biologist.

"When it comes to feral hogs in Texas, separating fact from fiction is becoming a little easier as research reveals more about the pesky porcines," said Dr. Billy Higginbotham, AgriLife Extension wildlife specialist. "There remains much we don’t know about this exotic that has inhabited our state for the past 450 years."

Highest ranking among the myths are estimates of the actual number of feral hogs in Texas, Higginbotham said. A common number that has been bandied about for years is 1 to 4 million. But there was just no data to support this estimate.

That is, not until Dr. Roel Lopez, associate director of the Texas A&M University Institute for Renewable Natural Resources, recently used geographic information system procedures to turn the guesstimates into reliable estimates, said Higginbotham, who collaborated with Lopez on the study.

The term "geographic information systems," usually simply called GIS, refers to a procedure that involves diverse data gathering means, from on-the-ground GPS referenced data to satellite to historical records, and organizes it geographically.

"A simpler way to put it is that it’s just an electronic map," Lopez said.

Using GIS techniques, Lopez was able to quantify first the extent of the feral hog habitat in Texas. He estimates that "approximately 134 million acres, or 79 percent of the state’s 170 million acres, represents feral hog habitat," said Higginbotham.

By knowing the range of feral hog habitat and the species population density in various types of Texas environments, Lopez also came up with a population estimate that has some meat to it, Higginbotham said. Lopez estimates that the actual number could range from a low of 1.9 million to a high of 3.4 million.

Exaggerated claims of feral hog population-growth rates are a related myth. Many of the population guesstimates are based on a purely arbitrary number of hogs in Texas being set at 1 million in the 1970s. This number, which also had no research basis, is then often extrapolated on using another bit of misinformation: That because of feral hogs' high birth rates, their population is doubling every year.

What are the facts?

A 2011 consolidation of past studies done by graduate student, Janell Mellish, the average litter size in Texas and the Southeast is 5.6 pigs, Lopez said.

It is also known, that on average, a sow is about 13 months old when she has her first litter, and also on average, mature sows have 1.5 litters per year. This means there is a significant population growth rate, but a far cry from the doubling-yearly myth, Lopez said.

"We estimated the population growth of feral hogs in Texas averages between 18 percent to 20 percent annually," Lopez said. "This means it would take almost five years for a population to double in size if left unchecked."

The study, which was conducted by Lopez and Mellish, used three methods to estimate feral pig population growth in Texas: the statewide number of aerial permits issued for shooting feral hogs; the number of pigs processed in commercial processing facilities; and feral hog control data made available from U.S. Department of Agriculture-Wildlife Services.

Another common myth is that recreational hunting alone can control feral hog populations, Higginbotham said.

"Of the dozen studies conducted across the nation, hunting removes between 8 percent and 50 percent of a population, with an average of 24 percent across all studies," he said. "In order to hold a population stable with no growth, 60 percent to 70 percent of a feral hog population would have to be removed annually."

Another myth is that it's possible to identify the breed of a given feral hog by its color markings.

"Today’s feral hogs are descended from domestic breeds, Eurasian wild boars and, of course, hybrids of the two," Higginbotham said. "But despite claims to the contrary, simply observing the color patterns, hair characteristics and size cannot let you definitively identify which of the three types an individual hog falls into."

Damage no myth

One thing about feral hogs is definitely not a myth—the huge amount of damage they do to crops, wildlife habitat and landscapes, Higginbotham said. And from all indications, the damage they do is expanding in scope and range.

"Feral hogs were once largely a rural or agricultural issue in Texas, inflicting over $52 million in damage annually," he said. "But the porkers have literally moved to town and are now causing significant damage in urban and suburban communities. This damage includes the rooting of landscapes, parks, lawns, golf courses, sports fields and even cemeteries, as they search for food. It has been estimated that a single hog can cause over $200 damage annually."

The $200-per-hog estimate doesn't include the damage feral hogs do as they compete with other wildlife species, such as whitetail deer, for food and habitat. And some of the species challenged by feral hog invasions are endangered.

It's important to keep in perspective that the bottom line is not an actual hog-head count, but the damage they do and how to develop ways to reduce it.

"For those landowners actively engaged in deer management, tolerance of feral hogs should be very, very low," Higginbotham said. "Can we (significantly) reduce the damage feral hogs do through control efforts? The answer is 'absolutely yes.'

"Texas AgriLife Extension Service has demonstrated that through education and outreach and Wildlife Services-led control efforts, damage can be significantly reduced by control efforts," he said. "In a 2006-07 study funded by the Texas Department of Agriculture, agricultural damage was reduced by 66 percent via control efforts in just two years."

Since 2007, subsequent studies done by AgriLife Extension and again funded by the state’s department of agriculture confirmed that control measures such as trapping and shooting "prevented millions of dollars in damage by reducing feral hog populations," he said.

"Landowners remain the first line of defense since Texas is 95 percent privately owned land," Higginbotham said. "This means arming the public with Best Management Practices and using various legal control methods to abate the damage by reducing feral hog populations."

For more information on feral hogs, visit the AgriLife Extension website, "Coping with Feral Hogs," at http://feralhogs.tamu.edu[2].